The present invention relates to method of making a shoe midsole, and more particularly to method of making an EVA foamed shoe midsole.
As shown in FIG. 1, the sole of a conventional athletic shoe of prior art is composed of a midsole 10 of wedge shape and an outsole 20. The midsole 10 is generally made of light material having substantial elasticity and toughness so as to afford wearing comfort. The outsole 20 is made of abrasion-resistant plastic material, which serves to prolong the life of shoe. As shown in FIG. 2, the prior art manufacturing process flow of an EVA foamed shoe midsole includes the following steps:
(1) preparing the mixture containing EVA, filling agent, foaming agent, and bridging agent in appropriate proportions; PA0 (2) agitating the mixture thoroughly so as to disperse its constituents evenly; PA0 (3) making piece bodies of predetermined thickness out of the cooled mixture by means of a rolling machine; PA0 (4) shaping the foamed compound into large pieces of thick foamed plates under pressure and heat; PA0 (5) cutting the large thick foamed plates into the midsole material plates 11 of appropriate sizes, as shown in FIG. 3; PA0 (6) cutting a midsole material plate 11 into two wedged material plates 12, each of which is composed of a bevel with a thin side 13 forming the sole portion of the midsole and a thick side 14 forming the heel portion of the midsole, as shown in FIG. 4; PA0 (7) cutting the wedged material plate 12 into a raw midsole blank 15 of a predetermined size, as shown in FIG. 5; PA0 (8) grinding the edge of the raw midsole blank 15 into a flat portion 16 so that a refined midsole blank 17 is formed, as shown in FIG. 6; and PA0 (9) placing the refined midsole blank 17 into a molding tool in which a midsole 30 is formed under heat and pressure and is shaped into a final form after being cooled, as shown in FIG. 7. PA0 (1) A substantial amount of raw material is wasted during cutting and grinding processes in steps 5, 7, and 8, as described above. PA0 (2) The substantial amounts of cost and labor are required for disposing properly of the waste materials produced during various stages of the manufacturing process. PA0 (3) The material dust produced during the grinding process of step 8, as described above, is hazardous to the health of workers. PA0 (4) The production rate of shoe midsole is slow in view of its complicated production process flow. PA0 (5) The material and labor costs are relatively high.
The shortcomings of the prior art manufacturing process of EVA shoe midsole described above can be summarized as follows: